1. Field of the Invention
The invention relates to an impedance matching network for matching the impedance of a radio frequency (RF) signal source to the impedance of a load and, more particularly, to high efficiency impedance matching networks.
2. Description of the Background Art
Radio frequency (RF) matching networks are used for coupling RF power, e.g., 13.56 MHz, from an RF source having a substantially resistive impedance (e.g., 50 ohms) to a load having a complex impedance. The matching network matches the source impedance to the load impedance to effectively couple RF power from the source to the load. In high power applications, such as coupling RF or microwave power to an antenna within a communications system, coupling RF power to a plasma within a plasma reaction chamber of a semiconductor wafer processing system and the like, the matching network should be relatively efficient, i.e., the contribution of the matching network to the total a loop resistance should be as small as possible. The resistance of the matching network produces heat and a loss of power coupled through the network. An inefficient matching network requires additional source power to overcome the losses in the matching network and additional cooling requirements to dissipate heat generated within the matching network. Conversely, optimizing the matching network losses results in additional transmitted power to the load. Such additional power provides increased etch rate within a plasma enhanced semiconductor wafer processing system, superior deposition resulting from a physical vapor deposition system, and the like. Empirical study of matching network losses has indicated that optimal network construction should minimize loop resistance and stray capacitances.
Therefore, a need exists in the art for an impedance matching network having improved efficiency.